The present application relates to vehicle air braking systems, and is particularly directed to a hybrid structural apparatus for a vehicle air braking system, such as a heavy vehicle air braking system that includes a drum brake assembly.
A typical drum brake assembly includes a brake shoe that engages a wheel drum to transmit braking torque through a brake spider to a wheel axle. One end of the brake shoe is pivotable against an anchor pin that is attached to one side of the brake spider. A cam follower roller is disposed at the other end of the brake shoe. When a service brake application occurs, a camshaft located on the side of the brake spider opposite the anchor pin is actuated to rotate about its longitudinal central axis. As the camshaft rotates about its longitudinal central axis, a cam surface of an S-cam mounted on the camshaft acts against the cam follower roller to pivot the brake shoe about the anchor pin. As the brake shoe pivots about the anchor pin, the lining of the brake shoe frictionally engages the wheel drum to transmit braking torque through the brake spider to the wheel axle and thereby to decelerate and brake the vehicle.
In S-cam drum brakes, a cam bracket supports and orients the camshaft and provides a mounting interface for a brake actuator. The cam bracket resists the torque of the camshaft and the linear load of the brake actuator, as well as any vibration-induced loads. Some known cam brackets are made entirely of either ferrous or aluminum alloys having dramatically different material properties. Accordingly, those skilled in the art continue with research and development efforts in cam brackets for S-cam drum brakes.